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From: "Mark Pearson" <mpearson-lenovo@squebb.ca>
To: "Greg KH" <gregkh@linuxfoundation.org>
Cc: "Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: typec: ucsi: Handle incorrect num_connectors capability
Date: Fri, 22 Aug 2025 08:54:22 -0400	[thread overview]
Message-ID: <0ac78125-a028-4d99-b106-d792d8660d0f@app.fastmail.com> (raw)
In-Reply-To: <2025082213-antacid-correct-53b1@gregkh>

Hi Greg,

On Fri, Aug 22, 2025, at 12:51 AM, Greg KH wrote:
> On Thu, Aug 21, 2025 at 02:53:07PM -0400, Mark Pearson wrote:
>> The UCSI spec states that the num_connectors field is 7 bits, and the
>> 8th bit is reserved and should be set to zero.
>> Some buggy FW has been known to set this bit, and it can lead to a
>> system not booting.
>> Flag that the FW is not behaving correctly, and auto-fix the value
>> so that the system boots correctly.
>> 
>> Found on Lenovo P1 G8 during Linux enablement program. The FW will
>> be fixed, but seemed worth addressing in case it hit platforms that
>> aren't officially Linux supported.
>> 
>> Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
>
> Any hints as to what commit id this fixes?
>
> thanks,
>
> greg k-h

Maybe 3cf657f ('Remove all bit-fields')?

The commit there states that 'We can't use bit fields with data that is received or send
to/from the device.'
Not sure why that is, but I assumed this means we shouldn't change the structure to use 7 bits for num_connectors, which was my original plan.

After that, we go all the way back to the file creation (c1b0bc2) where it was defined as 8 bit.

Mark

  reply	other threads:[~2025-08-22 12:54 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-21 18:53 Mark Pearson
2025-08-22  4:51 ` Greg KH
2025-08-22 12:54   ` Mark Pearson [this message]
2025-09-17 18:14     ` Mark Pearson
2025-09-18  7:50       ` Greg KH
2025-09-19  7:44         ` Heikki Krogerus
2025-09-19 15:45           ` Mark Pearson
2025-09-22 12:48             ` Heikki Krogerus
2025-09-29 19:25               ` Mark Pearson
2025-09-29 19:35                 ` Greg KH
2025-09-29 20:01                   ` Mark Pearson

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